The current Association of American Railroads (AAR) specification provides that special uncoupling devices for cars with sliding sill cushioned underframes, or cars with end-of-car cushioning, or cars with standard draft gears with increased angularity be able to unlock in all positions of the coupler with an uncoupling force of not more than forty (40) pounds.
A typical uncoupling device includes a pivoting handle on the side of the car and extends from the side of the car to the coupler lock lifter. A hook on the uncoupling device engages an opening in the lock lifter. When the handle is rotated the lock lifter is rotated about a horizontal axis to move the lock lifter connector vertically to unlock the coupler.
The coupler and shank can pivot horizontally up to 18 degrees on either side of the car center line and has a longitudial travel of up to .+-.20 inches. This varies the angle the uncoupling device makes with the lock lifter assembly from about 90 degrees at the center line of the car with cushion unit extended to about 120 degrees when the coupler shank is pivoted toward the side where the handle is located and the cushion unit is compressed, to about 75 degrees when the coupler shank is pivoted off the center line away from the uncoupling handle and the cushion unit is extended